Reliably transmitting high-quality audio-visual signals from a multimedia source to a multimedia sink has been a difficult undertaking as large amounts of data need to be transmitted at high data rates to yield crisp video images and audio sounds. Examples of such sources include DVD players, set-top boxes, audio/video (“A/V”) receivers, whereas examples of such sinks include high-definition (“HD”) television (or digital television, or “DTV”) and computer monitors and/or displays. Analog interfaces, such as composite, super video (“S-Video”) and component video interfaces, are traditionally used to transmit audio-visual signals. But the use of these analog interfaces, as well as digital-to-analog conversions used to generate the analog signals, contribute to degradation in signal quality. The degradation of signal quality can be further exacerbated when data compression is applied to audio and video signals.
One approach to ameliorate the drawbacks of the traditional transmission techniques has been the development of a High-Definition Multimedia Interface (“HDMI”), which specifies a protocol for transmitting uncompressed, high-quality digitized audio and video signals via a serial HDMI link. High-Definition Multimedia Interface Specification Version 1.0 was published on Dec. 9, 2002 and is available at www.hdmi.org. There are also HDMI specification versions 1.1, 1.2, 1.2a, 1.3 and 1.3a. Further, HDMI provides for a high-speed, high-quality serial link between HDMI transmitters (i.e., transmitters disposed within “HDMI sources,” such as television set-top boxes, DVD players, etc.) and HDMI receivers (i.e., receivers disposed within “HDMI sinks,” such as computer monitors, HDTVs and other HD video displays). Another standard for video is the Digital Visual Interface (DVI) revision 1.0 standard dated Apr. 2, 1999, available from the Digital Display Working Group at www.ddwg.org. Unified Display Interface (“UDI”) is another interface standard available from the UDI working group at www.udiwg.org. HDMI was design with the objective that its signals could be transmitted with a DVI transmitter.
Transition minimized differential signaling (TMDS) uses ten bits to represent eight bits and maintain a balance between the number of 0s and 1s in the signal over time to achieve a sustained average DC level. TMDS involves two stages. In the first stage, each bit is either XOR or XNOR transformed against the previous bit with the first bit not being transformed. The encoder chooses between XOR and XNOR by determining which will result in the fewest transitions with the ninth bit indicating which was used. In the second stage, the first eight bits are optionally inverted to even out the balance of ones and zeroes and achieve a sustained average DC level. The tenth bit indicates whether the inversion took place. An overview of TMDS is provided in the DVI revision 1.0 document dated Apr. 2, 1999, chapter 3. DVI and HDMI are each a TMDS-based signaling protocol.
DVO (digital video out) and SDVO (serial digital video out) are well known video connector ports developed by Intel Corporation for use in connection with motherboards.
Various low pin count devices have been proposed in which a narrow, high speed interface is used to communicate a wider group of signals between semiconductor chips (also called dies or dice).
HDMI transmitters typically include functional blocks both for formatting the data representing audio and video signals into HDMI-compliant signals and for serializing those signals. While HDMI transmitters are functional, their internal conventional structural links and processes for transferring data between those functional blocks do not readily facilitate the physical separation of those functional blocks while maintaining HDMI-compliant data transfers external to the transmitter.